2,277 research outputs found

    Affect Variability and Physical Health: The Moderating Role of Mean Affect

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    Research has only begun to explore how affect variability relates to physical health and has typically not assessed long-term associations nor considered the moderating role of mean affect. Therefore, we used data from the Midlife in the United States Study waves 2 (N = 1512) and 3 (N = 1499) to test how affect variability predicted concurrent and long-term physical health while also testing the moderating role of mean affect. Results indicated that greater negative affect variability was associated concurrently with a greater number of chronic conditions (p = .03) and longitudinally with worse self-rated physical health (p \u3c .01). Greater positive affect variability was associated concurrently with more chronic conditions (p \u3c .01) and medications (p \u3c .01) and longitudinally with worse self-rated physical health (p = .04). Further, mean negative affect played a moderating role such that at lower levels of mean negative affect, as affect variability increased, so did the number of concurrent chronic conditions (p \u3c .01) and medications (p = .03) and the likelihood of reporting worse long-term self-rated physical health (p \u3c .01). Thus, the role of mean affect should be considered when testing short- and long-term associations between affect variability and physical health

    Nernst Effect and Superconducting Fluctuations in Zn-doped YBa2_{2}Cu3_{3}O7δ_{7-\delta}

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    We report the measurements of in-plane resistivity, Hall effect, and Nernst effect in Zn doped YBa2_{2}Cu3_{3}O7δ_{7-\delta} epitaxial thin films grown by pulsed laser deposition technique. The pseudogap temperature, TT^*, determined from the temperature dependence of resistivity, does not change significantly with Zn doping. Meanwhile the onset temperature (TνT^{\nu}) of anomalous Nernst signal above Tc0T_{c0}, which is interpreted as evidence for vortex-like excitations, decreases sharply as the superconducting transition temperature Tc0T_{c0} does. A significant decrease in the maximum of vortex Nernst signal in mixed state is also observed, which is consistent with the scenario that Zn impurities cause a decrease in the superfluid density and therefore suppress the superconductivity. The phase diagram of TT^*, TνT^{\nu}, and Tc0T_{c0} versus Zn content is presented and discussed.Comment: 6 pages, 5 figures, Latex; v2: to be published in PR

    Superconductivity in the non-oxide Perovskite MgCNi3

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    The oxide perovskites are a large family of materials with many important physical properties. Of particular interest has been the fact that this structure type provides an excellent structural framework for the existence of superconductivity. The high Tc copper oxides are the most famous examples of superconducting perovskites, but there are many others [1]. Intermetallic compounds have been the source of many superconducting materials in the past, but they have been eclipsed in recent years by the perovskite oxides. The recent discovery of superconductivity in MgB2 [2] suggests that intermetallic compounds with simple structure types are worth serious reconsideration as sources of new superconducting materials. Here we report the observation of superconductivity at 8 K in the perovskite structure intermetallic compound MgCNi3, linking what appear at first sight to be mutually exclusive classes of superconducting materials. The observation of superconductivity in MgCNi3 indicates that MgB2 will not be the only one of its kind within the chemical paradigm that it suggests for new superconducting materials

    Large enhancement of the thermopower in Nax_xCoO2_2 at high Na doping

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    Research on the oxide perovskites has uncovered electronic properties that are strikingly enhanced compared with those in conventional metals. Examples are the high critical temperatures of the cuprate superconductors and the colossal magnetoresistance in the manganites. The conducting layered cobaltate NaxCoO2\rm Na_xCoO_2 displays several interesting electronic phases as xx is varied including water-induced superconductivity and an insulating state that is destroyed by field. Initial measurements showed that, in the as-grown composition, NaxCoO2\rm Na_xCoO_2 displays moderately large thermopower SS and conductivity σ\sigma. However, the prospects for thermoelectric cooling applications faded when the figure of merit ZZ was found to be small at this composition (0.6<x<<x<0.7). Here we report that, in the poorly-explored high-doping region x>x>0.75, SS undergoes an even steeper enhancement. At the critical doping xpx_p\sim 0.85, ZZ (at 80 K) reaches values \sim40 times larger than in the as-grown crystals. We discuss prospects for low-temperature thermoelectric applications.Comment: 6 pages, 7 figure

    Multi-sulfonated ligands on gold nanoparticles as virucidal antiviral for Dengue virus

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    Dengue virus (DENV) causes 390 million infections per year. Infections can be asymptomatic or range from mild fever to severe haemorrhagic fever and shock syndrome. Currently, no effective antivirals or safe universal vaccine is available. In the present work we tested different gold nanoparticles (AuNP) coated with ligands ω-terminated with sugars bearing multiple sulfonate groups. We aimed to identify compounds with antiviral properties due to irreversible (virucidal) rather than reversible (virustatic) inhibition. The ligands varied in length, in number of sulfonated groups as well as their spatial orientation induced by the sugar head groups. We identified two candidates, a glucose- and a lactose-based ligand showing a low EC50 (effective concentration that inhibit 50% of the viral activity) for DENV-2 inhibition, moderate toxicity and a virucidal effect in hepatocytes with titre reduction of Median Tissue Culture Infectious Dose log10TCID50 2.5 and 3.1. Molecular docking simulations complemented the experimental findings suggesting a molecular rationale behind the binding between sulfonated head groups and DENV-2 envelope protein
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